Semiconductor memory device and memory system including same

ABSTRACT

A method of operating a semiconductor memory device is provided as follows. The semiconductor memory device receive a bank address for a first bank including a first word line, a second word line and a third word line. The semiconductor memory device receive a first row address to activate the first world line for a read operation or a write operation. The semiconductor memory device generates a second row address to refresh a plurality of memory cells associated with the second word line.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119(a) to KoreanPatent Application No. 10-2014-0174189 filed on Dec. 5, 2014, thedisclosure of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present inventive concept relates to s a semiconductor memory deviceand a memory system including the same.

DISCUSSION OF RELATED ART

Dynamic random access memory (DRAM) cells store a charge amountcorresponding to data to be stored therein. The DRAM cells are refreshedperiodically to keep the data stored. However, when a high-speedoperation is required in the semiconductor memory device, time consumedfor the refresh causes the operation speed of the semiconductor memorydevice to decrease.

SUMMARY

According to an exemplary embodiment of the present inventive concept, amethod of operating a semiconductor memory device is provided asfollows. The semiconductor memory device receive a bank address for afirst bank including a first word line, a second word line and a thirdword line. The semiconductor memory device receive a first row addressto activate the first world line for a read operation or a writeoperation. The semiconductor memory device generates a second rowaddress to refresh a plurality of memory cells associated with thesecond word line.

According to an exemplary embodiment of the present inventive concept, asemiconductor memory device is provided as follows. A command decodergenerates an activation command. A bank activation logic receives a bankaddress and the activation command, generating a bank activation signal.Memory bank units include a first bank unit. If the bank addressindicates to the first bank unit, the first bank unit performs theactivation command and an active refresh operation and generates a firstrefresh done signal. If the bank address does not indicate to the firstbank unit for a predetermined time, the first bank unit performs aper-bank self-refresh operation. The performing of the activationcommand and the performing of the active refresh operation are initiatedby the bank activation signal.

According to an exemplary embodiment of the present inventive concept, asemiconductor memory system is provided as follows. A memory controllerissues a first activation command and a first row address. Asemiconductor memory receives the first activation command and the firstrow address, generates a second row address, activates the first wordline selected by the first row address and refreshes memory cellsassociated with the second row address. The refreshing and theactivating are initiated by the first activation command.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the inventive concept will become moreapparent by describing in detail exemplary embodiments thereof withreference to the accompanying drawings of which:

FIG. 1 is a schematic diagram of a memory system according to anexemplary embodiment of the present inventive concept;

FIG. 2 is a detailed block diagram of the memory system of FIG. 1according to an exemplary embodiment of the present inventive concept;

FIG. 3 is a detailed block diagram of a first bank unit of FIG. 2according to an exemplary embodiment of the present inventive concept;

FIG. 3A is an open bitline architecture of the first bank unit of FIG. 3according to an exemplary embodiment of the present inventive concept;

FIG. 4 is a timing diagram of an active refresh operation of asemiconductor memory device of FIG. 2 according to an exemplaryembodiment of the present inventive concept;

FIG. 5 is a timing diagram of the semiconductor memory device of FIG. 2according to an exemplary embodiment of the present inventive concept;

FIG. 6 is a timing diagram of a self-refresh operation of thesemiconductor memory device of FIG. 2 according to according to anexemplary embodiment of the present inventive concept;

FIG. 7 is a timing diagram of a self-refresh operation in thesemiconductor memory device of FIG. 2 according to an exemplaryembodiment of the present inventive concept;

FIG. 8 is a conceptual diagram of a method of addressing word lines in abank of FIG. 3 according to an exemplary embodiment of the presentinventive concept;

FIG. 9 is a detailed timing diagram of the self-refresh operation of thesemiconductor memory device of FIG. 2 according to an exemplaryembodiment of the present inventive concept;

FIG. 10 is a diagram of a computer system including the semiconductormemory device of FIG. 1 according to an exemplary embodiment of thepresent inventive concept;

FIG. 11 is a block diagram of a computer system including thesemiconductor memory device of FIG. 1 according to an exemplaryembodiment of the present inventive concept;

FIG. 12 is a block diagram of a computer system including thesemiconductor memory device of FIG. 1 according to an exemplaryembodiment of the present inventive concept;

FIG. 13 is a block diagram of a computer system including thesemiconductor memory device of FIG. 1 according to an exemplaryembodiment of the present inventive concept;

FIG. 14 is a block diagram of a computer system including thesemiconductor memory device of FIG. 1 according to an exemplaryembodiment of the present inventive concept;

FIG. 15 is a block diagram of a computer system including thesemiconductor memory device of FIG. 1 according to an exemplaryembodiment of the present inventive concept;

FIG. 16 is a block diagram of a data processing system including thesemiconductor memory device of FIG. 1 according to an exemplaryembodiment of the present inventive concept;

FIG. 17 is a schematic diagram of a multi-chip package including thesemiconductor memory device of FIG. 1 according to an exemplaryembodiment of the present inventive concept; and

FIG. 18 is a three-dimensional diagram of the multi-chip package of FIG.17 according to an exemplary embodiment of the present inventiveconcept.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments of the inventive concept will be described belowin detail with reference to the accompanying drawings. However, theinventive concept may be embodied in different forms and should not beconstrued as limited to the embodiments set forth herein. In thedrawings, the thickness of layers and regions may be exaggerated forclarity. It will also be understood that when an element is referred toas being “on” another element or substrate, it may be directly on theother element or substrate, or intervening layers may also be present.It will also be understood that when an element is referred to as being“coupled to” or “connected to” another element, it may be directlycoupled to or connected to the other element, or intervening elementsmay also be present. Like reference numerals may refer to the likeelements throughout the specification and drawings.

FIG. 1 shows a memory system 10 according to an exemplary embodiment ofthe inventive concept. The memory system 10 includes a plurality ofmemory modules 50 and a memory controller 300.

Each memory module 50 includes a plurality of dies RAM0 through RAMp.Each die corresponds to a semiconductor memory device. Each memorymodule 50 may be implemented as a single in-line memory module (SIMM) ora dual in-line memory module (DIMM).

The dies RAM0 through RAMp may operate in response to addressinformation ADD and a command signal CMD received from the memorycontroller 300 and may communicate a data signal DQ and a data strobesignal DQS with the memory controller 300. The data signal DQ mayinclude error information transmitted from the dies RAM0 through RAMp tothe memory controller 300. If a die does not process a command receivedfrom a memory controller due to an activation conflict, the die maygenerate error information to inform the memory controller that thecommand is not performed. In an exemplary embodiment, each die mayinclude a pin through which a memory controller detects the errorinformation from a die. The error information will be described indetail with reference to FIG. 9.

The memory controller 300 may control the overall operation of thememory module 50. The overall operation may include a read operation, awrite operation and/or a refresh operation. The memory controller 300may be implemented as a part of a system on chip (SoC) for a mobileapplication, for example.

FIG. 2 shows a block diagram of the memory system 10 of FIG. 1 accordingto an exemplary embodiment of the present inventive concept. FIG. 3shows a block diagram of a first bank unit 200A of FIG. 2. FIG. 3A showsa bank structure having an open-bit line architecture according to anexemplary embodiment. Referring to FIGS. 1 through 3, the memory system10 includes a semiconductor memory device 100 and the memory controller300. FIG. 2 shows a die (e.g., RAM0) included in the memory module 50 ofFIG. 1 and the memory controller 300. Elements 110 through 190 of FIGS.2 and 3 may be formed in software, hardware, or a combination thereof.

The semiconductor memory device 100 may include a command/address (C/A)sampler 110, a command decoder 120, a row address buffer 130, a bankactivation logic 140, a memory core 150, a counter block 160, atemperature compensate self-refresh (TCSR) unit 170, an errorinformation generator 180, and an error information driver 190.

The C/A sampler 110 may sample a command/address information CMD & ADDreceived from the memory controller 300 and may transmit the command CMDto the command decoder 120 and a row address RA to the row addressbuffer 130. The C/A sampler 110 may also transmit a bank address BA tothe bank activation logic 140.

The command/address information CMD & ADD may be formed of a packetincluding a command CMD and an address ADD. The sampling may be anoperation of separating the command CMD and the address ADD from thecommand/address information CMD & ADD. The command CMD is informationrequesting a particular operation of the semiconductor memory device100. The command CMD may include a read command, a write command, or anactivation command. The address ADD is information for selecting a bank,row and column addresses of a memory cell to be performed by the commandCMD. For example, the address ADD may include the row address RA and thebank address BA.

The command decoder 120 may interpret the command CMD and transmit acontrol signal to a logic that controls an operation corresponding tothe command CMD. For instance, when the command CMD is an activationcommand, the command decoder 120 may transmit an activation recognitionsignal ARS to the bank activation logic 140. The activation recognitionsignal ARS may be a signal generated from the command CMD including theactivation command. The command decoder 120 may also provide timing oferror information when the error information generator 180 generates theerror information.

The row address buffer 130 may temporarily store the row address RA andtransmit the row address RA to the memory core 150. The bank activationlogic 140 may generate bank activation signals BA_A through BA_H basedon the activation recognition signal ARS and the bank address BA toactivate at least one of a plurality of bank units BU_A through BU_H or200A through 200H included in the memory core 150. Each of the bankunits 200A through 200H may be independently selected using the bankaddress BA in response to the activation recognition signal ARS. Forexample, one bank may be selected or two or more banks may be selectedor all banks are selected. If all banks are selected, the bankactivation signals BA_A through BA_H may be at a high level at the sametime.

In response to the activation recognition signal ARS having a highlevel, the bank activation logic 140 may determine which of the bankunits 200A through 200H will be activated based on the bank address BA.The bank activation logic 140 may respond to the level of the activationrecognition signal ARS. For instance, if the bank address BAcorresponding to an activation command may correspond to the first andsecond bank units 200A and 200B, the bank activation signals BA_A andBA_B may the high level.

Alternatively, the bank activation logic 140 may respond to a transitionof the activation recognition signal ARS. For example, the bankactivation logic 140 may respond to, but is not limited to, a transitionof a low level to a high level of the activation recognition signal.

The bank activation logic 140 may also generate an activationimpossibility signal AIS if the bank activation logic 140 detects anactivation conflict. The bank activation logic 140 receives self-refreshsignals SELF_REF_A through SELF_REF_H, the activation recognition signalARS, and the bank address BA, and if detecting an activation conflict,transmits the activation impossibility signal AIS to the errorinformation generator 180. In this case, the self-refresh signalsSELF_REF_A through SELF_REF_H are internally generated from the counterblock 160. For instance, if the bank activation logic 140 receives thebank address BA corresponding to the first bank unit 200A and theactivation recognition signal ARS having the high level and if the firstbank unit 200A is performing a self-refresh operation on the first bankunit 200A in response to the first self-refresh signal SELF_REF_A havinga high level, the bank activation logic 140 may generate the activationimpossibility signal AIS having a high level to inform the memorycontroller 300 that the semiconductor memory device 100 is not able toperform a command on the first bank unit while performing theself-refresh on the first bank unit. The self-refresh operation will bedescribed with reference to FIG. 3 later.

The memory core 150 includes a plurality of the bank units 200A through200H. For example, the memory core 150 includes eight bank units 200Athrough 200H. The inventive concept is not limited thereto, and thenumber of the bank units may be less than or greater than eight.

The bank units 200A through 200H operate in substantially the samemanner, and for the convenience of descriptions, the operation of thefirst bank unit 200A only will be described with reference to FIG. 3.The first bank unit 200A includes a bank block 210, a row decoder block220, a decoder control block 240, and a bank control logic 250.

The bank block 210 includes a first bank BANK_A in which a plurality ofmemory cells 212 is arranged in a matrix. The memory cells 212 may storedata of at least one bit. The memory cells 212 may be implemented asnon-volatile memory cells that retain data even when power is cut off orvolatile memory cells that retain data only while power is beingsupplied. For example, the memory cells 212 may be dynamic random accessmemory (DRAM) cells, static RAM (SRAM) cells, synchronous DRAM (SDRAM)cells, electrically erasable programmable read-only memory (EEPROM)cells, flash memory cells, magnetic RAM (MRAM) cells, conductivebridging RAM (CBRAM) cells, ferroelectric RAM (FeRAM) cells,phase-change RAM (PRAM) cells, or resistive RAM (RRAM or ReRAM) cells.

In FIG. 3A, the first bank BANK_A is divided into a plurality of blocks211. Each of the blocks may have a sub-matrix form which includes memorycells 212 sharing a sub-word line driver 218 and a bitline senseamplifier 219. The sub-word line driver 218 of each block 211 drives aword line 213 within a block. The bitline sense amplifier 219 of eachblock 211 senses data on a local bit data line BL. Each block 211includes a sub-word line driver 218 and a bitline sense amplifier 219,and thus word lines and bit lines of each block 211 may be independentlycontrolled such that a read operation, a write operation, an eraseoperation, or a refresh operation is performed independently on eachblock 211. Each of the blocks may include 1024 word lines and 1024 bitlines.

The blocks are arranged in an open bit line structure sharing a bitlinesense amplifier between adjacent two blocks along a direction which aglobal bit line pair 214 including a global bit and a globalcomplementary bit line is extended. In the open bit line structure, eachbit line sense amplifier 219 is connected to a local bit line BL of afirst block and a local complementary bit line BL_B of a second blockadjacent to the first block. If two adjacent blocks are activated at thesame time or during an overlapped time, data corruption occurs due tothe sharing of the bitline sense amplifier 219. In this case, twoadjacent blocks are not activated at the same time or during anoverlapped time.

In this case, a local word line 213 a of each banks in the same row maybe electrically connected to a global word line 214 extending in a rowdirection. A local bitline 214 a of each block may be connected to aglobal bitline of the global bit line pair 214, extended in a columndirection, and a local complementary bitline 214 b of each block may beconnected to a global complementary bitline of the global bit line pair214 extended in the column direction.

Referring back to FIG. 3, the row decoder block 220 may include a firstrow decoder 222 and a second row decoder 224. The first row decoder 222may correspond to a row decoder 215 of FIG. 3A. For the convenience ofdescription, the first bank BANK_A includes 16 blocks BLK0 throughBLK15. However, the present inventive concept is not limited thereto,and the first bank BANK_A may include various numbers of blocks and bearranged in a matrix form.

The first row decoder 222 may include sub decoders 222_0 through 220_15which respectively activate the blocks BLK0 through BLK15. The subdecoders 222_0 through 222_15 of FIG. 3 may correspond to sub decoders215_0 through 215_15 of the row decoder 215 in FIG. 3A. Here, toactivate a block is to activate a word line included in a block inresponse to an activation command.

Each of the sub decoders 222_0 through 222_15 may activate one of theblocks BLK0 through BLK15 according to a normal activation address NAAand a first activation control signal AC1. The normal activation addressNAA may refer to an row address for a normal operation. For instance, ifthe normal activation address NAA corresponds to one of the word linesincluded in a block BLK0 and if the first activation control signal AC1is at a high level, the sub decoder 222_0 activates a word line in theblock BLK0 corresponding to the normal activation address NAA. A readoperation or a write operation may be performed on the activated wordline according to a read or write command. At this time, the sub decoder222_0 may transmit a block activation signal BLK_L0 to the second rowdecoder 224 to indicate that the block BLK0 has been activated.

The second row decoder 224 may include sub decoders 224_0 through 224_15which respectively activate the blocks BLK0 through BLK15. Each of thesub decoders 224_0 through 224_15 may selectively activate one of theblocks BLK0 through BLK15 according to a refresh activation address RAAand a second activation control signal AC2. The refresh activationaddress RAA may refer to an row address for an active refresh operation.For instance, if the refresh activation address RAA corresponds to oneof the word lines included in the block BLK8 and if the secondactivation control signal AC2 is at a high level, the sub decoder 224_8activates a word line in the block BLK8. A refresh operation may beperformed on the activated word line.

The refresh activation address RAA may include row address informationto be refreshed. In an exemplary embodiment, the refresh activationaddress RAA may include one row address information in a block or two ormore row address information to be refreshed in different blocks fromeach other. For example, if the refresh activation address RAA includesaddress information about two word lines included in different blocks,two different blocks are activated at the same time for a refreshoperation. In this case, the two different blocks may be selected amongblocks which are not performing a normal operation including a readoperation and/or a write operation.

The sub decoders 224_0 through 224_15 may selectively activate theblocks BLK0 through BLK15, respectively, based on block activationsignals BLK_0 through BLK_15 received from the first row decoder 222.

For instance, if the block activation signal BLK_0 is at a high leveland if the refresh activation address RAA corresponds to a word lineincluded in the block BLK0, the sub decoder 224_0 does not activate theblock BLK0 for a refresh operation because the block BLK0 is activatedfor a normal operation. In addition, if the block activation signalBLK_0 is at the high level and if the refresh activation address RAAincludes a word line included in the block BLK1 and a word line includedin BLK15, the sub decoder 224_0 does not activate the blocks BLK1 andBLK15. This is because if the first bank BANK_A has an open bit linestructure as shown in FIG. 3A, not only a block that has been activatedbut also blocks adjacent to the activated block cannot be activated atthe same time. If the blocks BLK1 and BLK15 adjacent to the block BLK0are activated for a refresh operation and if the block BLK0 is indicatedas having been activated by the block activation signal BLK_0, data of anormal operation is corrupted due to the sharing of bitline senseamplifier between the block BLK0 and the block BLK1 and between theblock BLK0 and the block BLK15. The “corrupted” means that reading ofdata from a memory cell is not properly performed or writing of datainto a memory cell is not properly performed. In this case, the blockBLK15 is adjacent to the block BLK0, and therefore, the blocks BLK15 andBLK0 cannot be activated at the same time. If two blocks shares abitline sense amplifier as shown in FIG. 3A, such two blocks may bereferred to be adjacent to each other. If the refresh activation addressRAA corresponds to a word line within a block to which a normaloperation is performed or a word line within a block adjacent to theblock of the normal operation, a block conflict occurs and a refreshoperation is prohibited to prevent data corruption of a normaloperation.

Once blocks among the blocks BLK0 through BLK15 corresponding to therefresh activation address RAA are activated, one or more sub decodersamong the sub decoders 224_0 through 224_15 associated with theactivated blocks may generate a refresh done signal REF_D_A. Forinstance, if the refresh activation address RAA includes addressescorresponding to the blocks BLK8 and BLK0 and if activation of bothblocks BLK0 and BLK8 is completed, the refresh done signal REF_D_Ahaving a high level may be generated. If at least one of the blocks BLK0and BLK15 has not been activated, the refresh done signal REF_D_A havinga low level may be generated.

The decoder block 220 includes two separated decoders of the first rowdecoder 222 and the second row decoder 224 which are physicallyseparated from each other. However, the inventive concept is not limitedthereto. For example, the decoder block 220 may be formed of a decodinglogic to be used for both a normal operation and a refresh operation. Inthis case, the decoding logic of the decoder block may serve as thefirst row decoder 222 and the second row decoder 224 in a time divisionmultiplexing method. In an exemplary embodiment, the decoder block 220may include a decoding logic shared by the first row decoder 222 and thesecond row decoder 224. In this case, a decoding operation for a normaloperation and a decoding operation for a refresh operation is performedin a time division multiplexing method.

The bank control logic 250 generates a bank control signal CTRL_A basedon the first self-refresh signal SELF_REF_A and the first bankactivation signal BA_A. For example, if one of the first self-refreshsignal SELF_REF_A and the first bank activation signal BA_A is at thehigh level, the bank control logic 250 may generate a bank controlsignal CTRL_A for activating word lines included in the first bankBANK_A. The bank control signal CTRL_A may include a plurality ofcontrol signals and information about which of the first self-refreshsignal SELF_REF_A and the first bank activation signal BA_A is at thehigh level.

The decoder control block 240 includes an activation controller 242, afirst address driver 244, a second address generator 315. In anexemplary embodiment, the second address generator 315 includes a secondaddress driver 246, and an adder 248. In an exemplary embodiment, thesecond address generator 315 may be implemented using a counter logic ofwhich a counter value increases or decreases in response to, forexample, the refresh done signal REF_D_A.

The activation controller 242 generates the first activation controlsignal AC1 and the second activation control signal AC2 based on thebank control signal CTRL_A. For example, if the bank control signalCTRL_A indicates that the first bank activation signal BA_A is at thehigh level and the first self-refresh signal SELF_REF is at the lowlevel, the activation controller 242 generates the first activationcontrol signal AC1 having the high level and the second activationcontrol signal AC2 having the high level. In this case, the bank controlsignal CTRL_A includes the first activation control signal AC1 and thesecond activation control signal AC2.

In this case, an activation command and an active refresh operation maybe performed as shown in FIG. 4. For example, the first bank activationsignal BA_A may initiate to perform the activation command on a wordline selected by the no activation address NAA and to perform the activerefresh operation on a word line selected by the refresh activationaddress RAA.

If a maximum refresh signal MAX_REF_A is at a high level, the activationcontroller 242 may generate the second activation control signal AC2having a low level. This is because a refresh operation is unnecessarywhen the maximum refresh signal MAX_REF_A is at the high level.

If the bank control signal CTRL_A indicates that the first self-refreshsignal SELF_REF_A is at the high level and the first bank activationsignal BA_A is at the low level, the activation controller 242 maygenerate the second activation control signal AC2 having the high level.For example, if the first self-refresh signal SELF_REF_A is at the highlevel, a self-refresh operation is performed on the bank 200A by thesecond row decoder 224. For this reason, only the second activationcontrol signal AC2 is at the high level.

The first address driver 244 may scramble the row address RA into thenormal activation address NAA and may transmit the normal activationaddress NAA to the first row decoder 222 in synchronization with thefirst activation control signal AC1. At least two bits of the rowaddress RA may be switched to each other to generate the normalactivation address NAA. The address scrambling will be described indetail with reference to FIG. 8.

The second address driver 246 provides the refresh activation addressRAA for the second row decoder 224. The second address driver 246 alsoprovides the refresh activation address RAA to the adder 248 as acurrent refresh address REFA_C. The adder 248 may generate a nextrefresh address REFA_A by adding a predetermined number to the currentrefresh address REFA_C. For example, the predetermined number may be one(1). An initial refresh activation address, i.e., the refresh activationaddress RAA may be randomly determined. Alternatively, the initialrefresh activation address may be predetermined to be a specificaddress.

The second address driver 246 provides the next refresh address REFA_Ato the second row decoder 224 as the new refresh activation address RAAin synchronization with the second activation control signal AC2. Thesecond address driver 246 may determine whether a refresh operation hasbeen performed with respect to the refresh activation address RAA basedon the refresh done signal REF_D_A and may store the determinationresult. For instance, if the refresh activation address RAA correspondsto a word line included in the block BLK0 which has been activated for anormal operation, a refresh operation based on the refresh activationaddress RAA is prohibited. In this case, the refresh done signal REF_D_Ais at the low level, and the refresh activation address RAAcorresponding to the word line may be provided to the second addressdriver 246 in a following refresh operation.

In the operation of the first bank unit 200A, if an activation commandis received from the memory controller 300, the first row decoder 222may activate a word line corresponding to the normal activation addressNAA according to the control of the activation controller 242 andsimultaneously the second row decoder 224 may activate a word linecorresponding to the refresh activation address RAA according to thecontrol of the activation controller 242. For example, if thesemiconductor memory device 100 receives an activation command of a readoperation or a write operation, activation of a word line correspondingto the activation command may be performed simultaneously with a refreshoperation on a word line included in a block different from the blockthat includes the word line activated by the activation command or ablock which is not adjacent to the block including the word lineactivated in a bank unit for a read operation or a write operation. Sucha refresh operation may be referred to as an active refresh operation.According to an exemplary embodiment, the active refresh operation isperformed without a control from the memory controller 300.

Without control of the memory controller 300, the second row decoder 224may activate a word line corresponding to the refresh activation addressRAA according to the control of the activation controller 242 based onthe first self-refresh signal SELF_REF_A which is internally generatedby the counter block 160 of FIG. 2. Such a refresh operation may bereferred to as a self-refresh operation. In an exemplary embodiment, theself-refresh operation may be performed in a unit of a bank in responseto self-refresh signal SELF_REF_A through SELF_REF_H generated from thecounter block 160. Hereinafter, the self-refresh signal may be referredto as a per-bank self-refresh signal or a per-bank self-refresh command.

The counter block 160 includes a plurality of pull-in counters 165Athrough 165H. The pull-in counters 165A through 165H are associated withthe bank units BU_A through BU_H, respectively. The pull-in counters165A through 165H may count refresh done signals REF_D_A throughREF_D_H, respectively. Each of the refresh done signals REF_D_A throughREF_D_H indicates whether a refresh operation has been completed or not.The pull-in counters 165A through 165H may store count values,respectively. The pull-in counters 165A through 165H may have a maximumvalue and a minimum value. For instance, the maximum value may be 7 andthe minimum value may be 0. However, the inventive concept is notlimited thereto, and the maximum and minimum values may be smaller orgreater than 7.

As shown in FIG. 2, each bank has an independent counter to monitor thestatus of an active refresh operation on the bank. For example, thefirst bank unit 200A is coupled to the first pull-in counter 165A. Inresponse to REF_D_A, shown in FIG. 3, generated from the second rowdecoder 224 of the first bank unit 200A, the first pull-in counter 165Aincreases its counter value stored therein. Similarly, the remainingbank units 200B to 200H are coupled to the remaining pull-in counters165B to 165H, respectively. For the convenience of description, furtherdescriptions of the remaining bank units 200B to 200H and the remainingpull-in counters 165B to 165H are omitted herein. Hereinafter, for theconvenience of description, an operation of the first pull-in counter165A will be described.

If the count value of the pull-in counter 165A reaches the maximumvalue, the pull-in counter 165A may generate a maximum refresh signalMAX_REF_A. In response to the maximum refresh signal MAX_REF_A, thesecond row decoder 224 of the first bank unit 200A does not perform anactive refresh operation. If the count value of the pull-in counter 165Areaches the minimum value, the pull-in counter 165A may generate theself-refresh signals SELF_REF_A. In this case, the first bank unit 200Ais in a refresh starvation, and if memory cells within the first bankunit 200A are not refreshed, the memory cells lose data stored therein.In response to the self-refresh signal SELF_REF_A, the second rowdecoder 224 may perform a self-refresh operation on the first bank unit200A. The operation of the pull-in counter 165A will be furtherdescribed with reference to an exemplary embodiment of FIG. 5.

The other pull-in counters 165B to 165H may operate as described abovewith respect to the first pull-in counter 165A, and thus furtherdescriptions of the other pull-in counters 165B to 165H are omittedherein for the convenience of the descriptions.

The TCSR unit 170 may generate a refresh clock signal CLK_REF of which aperiod is a refresh time interval (tREFI in FIG. 5). The refresh timeinterval tREFI is an average periodic refresh interval time. Forinstance, the memory cells of the first bank unit 200A are to berefreshed within a refresh window tREFW to keep data stored therein, andthus the refresh time interval tREFI is calculated by dividing therefresh window tREFW with the number of total word lines in the firstbank unit 200A. The refresh window tREFW may refer to cell retentiontime for which data stored in a memory cell is preserved without beingrefreshed. If the first bank unit 200A includes 16 blocks and if eachblock includes 1024 word lines and if the refresh window tREFW is 64milliseconds, the refresh time interval tREFI may be 3.9 μs. The refreshwindow tREFW may vary with the internal temperature of the semiconductormemory device 100, and thus the refresh time tREFI may vary the internaltemperature of the semiconductor memory device 100 as well. When theinternal temperature of the semiconductor memory device 100 increases,the refresh time interval tREFI may decrease. The inventive concept isnot limited thereto, and thus the refresh window tREFW and the number ofword lines may vary.

The pull-in counters 165A through 165H may detect an edge (e.g., arising edge) of the refresh clock signal CLK_REF and decrease the countvalue by a predetermined value (e.g., 1) at each detection of the risingedge, for example. In the case, the detection of the rising edge meanselapse of the refresh time interval tREFI.

The error information generator 180 generates error information EI whichis driven by the error information driver 190 to the memory controller300. In response to an activation impossibility signal AIS having a highlevel, the error information generator 180 generates the errorinformation EI. If the bank activation logic receives an activationcommand for the bank unit BU_A to which a self-refresh operation isbeing performed, the bank activation logic 140 generates the activationimpossibility signal AIS having the high level and the error informationgenerator 180 generates the error information EI to notify the memorycontroller that the bank unit BU_A is being performed by theself-refresh operation and thus a read operation or a write operation tothe bank unit BU_A requested by the memory controller is not performeduntil the self-refresh operation is completed. As shown in FIG. 9, theerror information generator 180 may generate the error information EIhaving a predetermined error latency for the activation command receivedfrom the command decoder 120. In an exemplary embodiment, the memorycontroller 300 may identify which active command is not performed bymeasuring the predetermined error latency.

The error information driver 190 may sense and amplify the errorinformation EI and may transmit the error information EI to the memorycontroller 300 in a digital format. The memory controller 300 mayrecognize based on the error latency of the error information EI whichactivation command of a read operation or a write operation has not beenperformed due to a self-refresh operation. The memory controller 300 mayreissue the activation command which was not performed to thesemiconductor memory device 100.

The memory controller 300 includes an error handler 310 and a scheduler320. The error handler 310 receives the error information EI from thesemiconductor memory device 100, and identify the activation commandhaving an activation conflict based on the error latency as shown inFIG. 9. In this case, the scheduler 320 may hold the activation command,and reissue the activation command to the semiconductor memory device100 after the self-refresh operation is completed.

According to an exemplary embodiment, the semiconductor memory device100 may perform a refresh operation without receiving a separate refreshcommand from the memory controller 300. For example, the active refreshoperation and the self-refresh operation are performed without anyinstruction from the memory controller. The active refresh operation isinternally performed in the same bank where a read or write operation isperformed. For example, in response to an activation command of a reador write operation, the active refresh operation is performed. Inaddition, the refresh operation is performed without control of a memorycontroller in the background in one bank in which a word line is beingactivated according to an activation command for a normal operation, sothat the operation speed of the semiconductor memory device 100 isincreased.

FIG. 4 is a timing diagram showing an active refresh operation of thesemiconductor memory device 100 of FIG. 2 according to an exemplaryembodiment. FIG. 5 is a timing diagram showing how counter values changein the operation of the semiconductor memory device 100 of FIG. 2.

Referring to FIGS. 1 through 5, FIG. 4 shows that activation commandsfor the first bank BANK_A are received at each row cycle time tRC. Therow cycle time tRC is a minimum period or a minimum number of cyclesnecessary for a memory to complete a read or write operation. A readoperation is completed by performing an activation command, a readcommand and a precharge command. A write operation is completed byperforming an activation command, a write command and a prechargecommand. The commands for the read or write operation are performedwithin the row cycle time tRC. In this case, the activation commandsACT-A are received at each start timing of the row cycle time tRC. Forthe convenience of description, the read command, the write command andthe precharge command are not shown on FIG. 4. Here, receiving anactivation command is denoted by ACT-A and starting an active refresh inresponse to the activation command is denoted by REF_ACT-A.

An activation signal is a conceptual signal indicating whether a row inthe first bank BANK_A is activated or not. During the high level of theactivation signal, the row in the first bank BANK_A is activated. Duringthe low level of the activation signal, the row in the first bank BANK_Ais precharged or not activated.

A refresh signal is a conceptual signal indicating whether a row in thefirst bank BANK_A is refreshed or not. The activation signal may be at ahigh level when the row in the first bank BANK_A is refreshed and may beat a low level when any of the rows in the first bank BANK_A is notrefreshed. In other words, the refresh signal informs whether a refreshoperation is performed when a row in the first bank BANK_A is activated.The activation signal and the refresh signal may be internally generatedby the bank control logic 250.

If an activation command for the first bank BANK_A is received at a timepoint t0, a row (or a word line) corresponding to the normal activationaddress NAA is activated in response to the activation command, and anactive refresh operation corresponding to the refresh activation addressRAA may be performed in the first bank unit 200A. The activationoperation and the active refresh operation may end at a time point t1when a precharge command is received.

When a new activation command for the first bank BANK_A is received at atime point t2, an operation of activating a row corresponding to the newnormal activation address NAA and an active refresh operationcorresponding to the new refresh activation address RAA may be performedin the first bank unit 200A.

Operations similar to those performed at the time points t1 and t2 maybe repeated at following time points t3 and t4. In an exemplaryembodiment, if an activation command for the first bank BANK_A isreceived, an operation of activating a row corresponding to the normalactivation address NAA and an active refresh operation corresponding tothe refresh activation address RAA may be performed simultaneously.Alternatively, the active refresh operation of the refresh address RAAmay be performed a predetermined time after the operation of activatingthe row of the normal activation address NAA is performed. For example,if the activation command for the first bank BANK_A is received, bothactive refresh operation and the normal activation operation areperformed with a predetermined time delay.

FIG. 5 shows how a counter value of a pull-in counter 165A changesaccording to an operation of the semiconductor memory device 100 ofFIG. 1. For the convenience of description, it is assumed that a firstbank unit 200A is activated. The refresh clock signal CLK_REF has aperiod of the refresh time interval tREFI and a count value Value_PIC isa count value stored in the first pull-in counter 165A. The temperaturecompensate self-refresh (TCSR) unit 170 generates the refresh clocksignal CLK_REF based on the refresh time interval tREFI and the internaltemperature of the semiconductor memory device 100.

The count value Value_PIC decreases as the refresh time interval tREFIhas elapsed, and the count value Value PIC increases if an activerefresh operation has performed. For the convenience of description, thecount value Value_PIC is assumed to decrease in response to a risingedge of the refresh clock signal CLK_REF. The present inventive conceptis not limited thereto, and the count value Value_PIC may decrease inresponse to a falling edge of the refresh clock signal CLK_REF. For theconvenience of description, it is assumed that an activation command fora read operation or a write operation is performed on a first block BLK0of the first bank 200A.

As shown in FIG. 5, at time point t0, the count value Value_PIC decreasefrom 6 to 5 in response to the rising edge of the refresh clock signalCLK_REF. For the convenience of description, the starting value of thecount value Value_PIC is 6, but the present inventive concept is notlimited thereto. At time point t1, an activation command with respect tothe normal activation address NAA and an active refresh operation withrespect to the block BLK6 corresponding to the refresh activationaddress RAA may be performed simultaneously at the time point t1. Inthis case, there is no conflict between the block BLK0 for the normalactivation operation of a read operation or a write operation and theblock BLK6 for the active refresh operation performed with the normalactivation operation. As the active refresh operation is performed onthe first bank 200A, the count value Value_PIC of the first bank unit200A is increased from 5 to 6.

At time point t2, an operation of activating a row within the block BLK0according to the normal activation address NAA and an active refreshoperation on the block BLK14 corresponding to the refresh activationaddress RAA may be performed simultaneously, for example. In this case,there is no conflict between the first block BLK0 and the block BLK14.As the active refresh operation is performed, the count value Value_PICis increased from 6 to 7 and the maximum refresh signal MAX_REF_Atransits to the high level, which represents that memory cells of thefirst bank unit 200A are all refreshed within a refresh window tREFW.

At time point t3, the refresh time tREFI has elapsed and the count valueValue_PIC decreases from 7 to 6. Accordingly, the maximum refresh signalMAX_REF_A transits to the low level.

At time point t4, an operation of activating a row corresponding to thenormal activation address NAA and an active refresh operation on theblock BLK5 corresponding to the refresh activation address RAA may beperformed simultaneously at the time point t4. As the active refreshoperation is performed, the count value Value_PIC is increased from 6 to7 and the maximum refresh signal MAX_REF_A transits to the high level.

At a time point t5, an operation of activating a row corresponding tothe normal activation address NAA is performed, but since the maximumrefresh signal MAX_REF_A is at the high level, an active refreshoperation is not performed according to the control of the activationcontroller 242. Such a process in which an active refresh operation isnot performed according to the maximum refresh signal MAX_REF_A isdenoted by MAX_CNT. This process is provided to prevent powerconsumption of the semiconductor memory device 100 from increasing dueto unnecessary refresh operations.

Since the refresh time tREFI has elapsed at the time point t6, the countvalue Value_PIC decreases from 7 to 6. Accordingly, the maximum refreshsignal MAX_REF_A transits to the low level.

If a row corresponding to the normal activation address NAA is includedin the block BLK0 at a time point t7, an operation of activating the rowis performed, but an active refresh operation of the block BLK1including a row corresponding to the refresh activation address RAA isnot performed simultaneously since the block BLK1 is adjacent to theblock BLK0. Such a phenomenon in which an active refresh operation isnot performed due to block conflict is denoted by BLK_CNF. Thisphenomenon may happen when the first bank BANK_A has an open bit linestructure.

Thereafter, operations similar to those performed at the time points t0,t1, and t3 may be repeated at following time points t8 through t10.

FIG. 6 is a timing diagram of a self-refresh operation in thesemiconductor memory device 100 of FIG. 2 according to an exemplaryembodiment of the present inventive concept. FIG. 7 is a timing diagramof a self-refresh operation in the semiconductor memory device 100 ofFIG. 2 according to an exemplary embodiment of the present inventiveconcept. FIG. 8 shows a method of addressing word lines in the firstbank BANK_A of FIG. 3. FIG. 9 is a timing of a self-refresh operation inthe semiconductor memory device 100 of FIG. 2 according to an exemplaryembodiment of the present inventive concept.

Referring to FIGS. 1 through 9, FIG. 6 shows the timing diagram of theself-refresh operation of the semiconductor memory device 100 when thefirst bank BANK_A is in a refresh starvation wherein a refresh operationis performed on the first bank BANK_A within a refresh window tREFW. Aself-refresh period tSREF is duration from the start of a self-refreshoperation on a block to a time when activation of the block for a normaloperation becomes possible after the self-refresh operation ends. Thecommence of a self-refresh operation is denoted by REF_SELF-A.

As an activation command for a bank BANK_B is received at the time pointt0, the second bank unit 200B may perform an operation of activating arow in a second bank (not shown) and an active refresh operation. As therefresh time tREFI has elapsed, the count value Value_PIC associatedwith the first bank BANK_A decreases from 6 to 5 at the time point t1.

As an activation command for a bank BANK_C is received at the time pointt2, the third bank unit 200C may perform an operation of activating arow in a third bank (not shown) and an active refresh operation. As therefresh time tREFI has elapsed, the count value Value_PIC associatedwith the first bank BANK_A decreases from 5 to 4 at the time point t3.An activation command for the bank BANK_A has not been issued beforetime t4, and thus the count value Value_PIC decreases to 0 at time t4.

Accordingly, the self-refresh signal SELF_REF_A transits to the highlevel at time t4. As the self-refresh signal SELF_REF_A transits to thehigh level, the first bank unit 200A may perform a self-refreshoperation on the first bank BANK_A using the refresh activation addressRAA which is internally generated.

When the self-refresh operation is completed at the time point t5, thefirst pull-in counter 165A may reset the count value Value_PIC to 7. Thereset value is not restricted to 7 and may be randomly determined.

As the refresh time tREFI has elapsed, the count value Value_PICdecreases from 7 to 6 at the time point t6. As an activation command forthe bank BANK_A is received at the time point t7, the first bank unit200A may perform an operation of activating a row corresponding to thenormal activation address NAA and an active refresh operationcorresponding to the refresh activation address RAA. At this time, asthe active refresh operation is performed, the count value Value_PICincreases from 6 to 7.

If the bank BANK_A is in a refresh starvation, a self-refresh operationis performed on the bank BANK_A. The refresh starvation may bedetermined using the first pull-in counter 165A, and thus if an activerefresh is performed mainly on a specific bank within a refresh windowtREFW, a self-refresh operation is performed on the remaining bank whichis in a refresh starvation.

FIG. 7 shows the timing diagram of the self-refresh operation of thesemiconductor memory device 100 if block conflict occurs between thefirst bank BANK_A and other banks adjacent to the first bank BANK_A. Ifan activation command for the bank BANK_A is received at the time pointt0, an operation of activating a row corresponding to the normalactivation address NAA may be performed, but an active refresh operationis not performed because of block conflict in which a block including arow corresponding to the refresh activation address RAA is adjacent to ablock including a row corresponding to the normal activation addressNAA. The block where an active refresh operation is prohibited due tothe block conflict may be referred to a keep-out zone.

As the refresh time tREFI has elapsed, the count value Value_PICdecreases from 6 to 5 at the time point t1.

When an activation command for the bank BANK_A is received at the timepoint t2 like at the time point t0, an operation of activating a rowcorresponding to the normal activation address NAA may be performed, butan active refresh operation is not performed because of block conflictin which a block including a row corresponding to the refresh activationaddress RAA is in a keep-out zone.

As the refresh time tREFI has elapsed, the count value Value_PICdecreases from 5 to 4 at the time point t3. If a block conflict occurson the first bank BANK_A until time t4,

the count value Value_PIC of the first bank unit BANK_A decreases to 0at the time point t4. Accordingly, the self-refresh signal SELF_REF_Atransits to the high level. As the self-refresh signal SELF_REF_Atransits to the high level at the time t4, the first bank unit 200A mayperform a self-refresh operation corresponding to the refresh activationaddress RAA on the first bank unit BANK_A.

If the self-refresh operation is completed at the time point t5, thefirst pull-in counter 165A may reset the count value Value_PIC to 7. Thereset value is not restricted to 7 and may be randomly determined. Thereset value may be changed after a predetermined delay when necessary(for example, according to the control of the TCSR unit 170 wheninternal temperature is very high or rapidly changes).

As the refresh time tREFI has elapsed, the count value Value_PICdecreases from 7 to 6 at the time point t6. As an activation command forthe bank BANK_A is received at the time point t7, the first bank unit200A may perform an operation of activating a row corresponding to thenormal activation address NAA and an active refresh operationcorresponding to the refresh activation address RAA. At this time, asthe active refresh operation is performed, the count value Value_PICincreases from 6 to 7.

If block conflict continues to occur on a bank without an active refreshoperation for a refresh window tREFW, a self-refresh operationcorresponding to the refresh activation address RAA may be performedusing the first pull-in counter 165A on the bank to refresh data storedin memory cells of the bank.

FIG. 8 shows a method of addressing word lines in the blocks BLK0through BLK15 of the bank BANK_A according to an exemplary embodiment ofthe present inventive concept. For the convenience of description, it isassumed that the number of word lines included in each of the blocksBLK0 through BLK15 is 1024. In this case, a total number of word linesincluded in the bank BANK_A is 16*1024.

If the memory controller 300 accesses to memory cells of which rowaddresses RA are localized within a narrow row address space for arefresh window tREFW, the data may be stored in memory cells of whichrow addresses RA may change sequentially. In this case, the memorycontroller 300 access to a specific block only within a bank unitwithout accessing other blocks, and thus the bank unit is subject torefresh starvation. To avoid such refresh starvation, a self-refreshoperation is performed on the bank. For instance, if a row address RAchanges sequentially in a first bank BANK_A, and if the row address RAincludes 100 rows within the first block BLK0 only to be accessed for arefresh window tREFW, an active refresh operation cannot be performed onthe first block BLK0 and the blocks BLK1 and BLK15 which are adjacent tothe first block BLK0 for the refresh window tREFW. The BLK1 and BLK15are within a keep-out zone of the first block BLK0. In this case, thesemiconductor memory device 100 may performs a self-refresh operation onthe first bank BANK_A to prevent data loss of the blocks BLK1 and BLK15without control of the memory controller 300. In an exemplaryembodiment, the self-refresh operation may be performed so thatremaining row addresses other than the localized row addresses arerefreshed to avoid refresh starvation. For example, memory cellsassociated the remaining row addresses may be refreshed within therefresh window tREFW by the self-refresh operation.

To avoid such address localization in a specific block in a bank unit,the row address RA is scrambled such that memory access by a memorycontroller is spread out among the blocks BLK0 through BLK15 in a firstbank BANK_A, for example. For the convenience of description, the rowaddress RA is assumed to is made up of 16 bits and the first bank BANK_Aincludes 16 blocks BLK0 through BLK15. In this case, the row address RAis scrambled such that four consecutive upper bits including the mostsignificant bit (MSB) and four consecutive lower bits including theleast significant bit (LSB) are switched. Without the scrambling, thefour consecutive upper bits may be used to select one of the 16 blocksBLK0 to BLK15 and the four consecutive lower bits may be used to selecta block selected by the four consecutive upper bits. Accordingly, if therow address RA change sequentially, memory access is localized into aspecific block. In an exemplary embodiment, the scrambling may move thefour consecutive lower bits into higher bit positions and the fourconsecutive upper bits into lower bit positions. Accordingly, if the rowaddress RA changes sequentially, the block address of the scrambledaddress continues to change such that memory access is spread out amongthe blocks BLK0 through BLK15 of the first bank unit BANK_A. In detail,when the LSB has a value of RA0 (e.g., 1) or RA0B (e.g., 0), the bit maybe addressed to distinguish the blocks BLK0 through BLK7 from the blocksBLK8 through BLK15. When the first upper bit than the LSB has a value ofRA1 (e.g., 1) or RA1B (e.g., 0), the bit may be addressed to distinguishthe blocks BLK0 through BLK3 from the blocks BLK4 through BLK7 ordistinguish the blocks BLK8 through BLK11 from the blocks BLK12 throughBLK15. When the second and third upper bits than the LSB are addressedin such a manner, all of the blocks BLK0 through BLK7 and BLK8 throughBLK15 may be distinguished from one another by the four bits.

When the row address RA addressed in this manner is used and data isstored at the row address RA, which changes sequentially when viewedfrom the perspective of the memory controller 300, in the bank BANK_A,the data may be stored among the blocks BLK0 to BLK15 without beingstored in a specific block only.

If the row address RA is scrambled in the above-described manner,refresh starvation of a bank may be less likely to happen compared to arow address without address scramble. In addition, when a rowcorresponding to the normal activation address NAA is the same as oradjacent to a row corresponding to the refresh activation address RAA,continuous block conflict may be prevented.

FIG. 9 is the timing diagram of an error information signal generatedduring a self-refresh period tSREF according to an exemplary embodiment.If an activation command is in conflict with a self-refresh, a memorycontroller detects which activation command is in conflict, waits untilthe self-refresh operation is completed, and then re-issue theactivation command An operation of receiving a write command for thethird bank unit 200C is denoted by WR-C, an operation of receiving aread command for the third bank unit 200C is denoted by RD-C, and anoperation of receive a read command for the first bank unit 200A isdenoted by RD-A.

At the time point t0, a write command for the third bank unit 200C isreceived and the third bank unit 200C starts a write operationcorresponding to the write command. As the self-refresh signalSELF_REF_A transits to the high level at the time point t1, the firstbank unit 200A starts a self-refresh operation corresponding to therefresh activation address RAA. As an active command for the first bankunit 200A is received at the time point t2 during the self-refreshoperation on the first bank unit 200A, the bank activation logic 140generates the activation impossibility signal AIS at the high level.

As a read command for the third bank unit 200C is received at the timepoint t3 during the self-refresh operation on the first bank unit 200A,the third bank unit 200C starts a read operation corresponding to theread command. At the time point t4, the error information generator 180may generate the error information EI having a predetermined errorlatency Error_Latency for the activation command causing the errorinformation EI.

As a read command for the first bank unit 200A is received at the timepoint t5 during the self-refresh operation on the first bank unit 200A,the bank activation logic 140 generates the activation impossibilitysignal AIS at the high level.

At the time point t6, the self-refresh operation on the first bank unit200A ends. At the time point t7, the error information generator 180 maygenerate the error information EI having the predetermined error latencyError_Latency for the read command causing the error information EI.

At the time point t8, the memory controller 300 may recognize that theactivation command issued for the first bank unit 200A at the time pointt2 has not been processed based on the error latency Error_Latency ofthe error information EI. Accordingly, the memory controller 300 mayreissue the activation command for the first bank unit 200A after theself-refresh period tSREF ends.

FIG. 10 is a diagram of a computer system 400 including thesemiconductor memory device 100 of FIG. 1 according to an exemplaryembodiment of the present inventive concept. Referring to FIGS. 1 and10, the computer system 400 may be implemented as a cellular phone, asmart phone, a personal digital assistant (PDA), or a wirelesscommunication device.

The computer system 400 includes the semiconductor memory device 100 anda memory controller 420 controlling the operation of the semiconductormemory device 100. The memory controller 420 may control a data accessoperation, e.g., a write operation or a read operation, of thesemiconductor memory device 100 according to the control of a host 410.The memory controller 420 may be the memory controller 300 illustratedin FIG. 1.

Data of the semiconductor memory device 100 may be displayed through adisplay 430 according to the control of the host 410 and the memorycontroller 420. A radio transceiver 440 may transmit or receive radiosignals through an antenna ANT. The radio transceiver 440 may convertradio signals received through the antenna ANT into signals that may beprocessed by the host 410. Accordingly, the host 410 may process thesignals received from the radio transceiver 440 and transmit theprocessed signals to the memory controller 420 or the display 430. Thememory controller 420 may store the signals processed by the host 410 inthe semiconductor memory device 100. The radio transceiver 440 may alsoconvert signals received from the host 410 into radio signals and outputthe radio signals to an external device through the antenna ANT.

An input device 450 may control the operation of the host 410 or data tobe processed by the host 410 to be input to the semiconductor memorydevice 100. The input device 450 may be implemented as a pointing devicesuch as a touch pad or a computer mouse, a keypad, or a keyboard.

The host 410 may control the operation of the display 430 to displaydata output from the memory controller 420, data output from the radiotransceiver 440, or data output from the input device 450. The memorycontroller 420, which controls the operations of the semiconductormemory device 100, may be implemented as a part of the host 410 or as aseparate chip.

FIG. 11 is a block diagram of a computer system 500 including thesemiconductor memory device 100 of FIG. 1 according to an exemplaryembodiment of the present inventive concept. The computer system 500 maybe implemented as a personal computer (PC), a tablet PC, a net-book, ane-reader, a personal digital assistant (PDA), a portable multimediaplayer (PMP), an MP3 player, or an MP4 player.

The computer system 500 includes a host 510, the semiconductor memorydevice 100, a memory controller 520 controlling the data processingoperations of the semiconductor memory device 100, a display 530 and aninput device 540.

The host 510 may display data stored in the semiconductor memory device100 through the display 530 according to data input through the inputdevice 540. The input device 540 may be implemented by a pointing devicesuch as a touch pad or a computer mouse, a keypad, or a keyboard.

The host 510 may control the overall operation of the computer system500 and the operations of the memory controller 520. The memorycontroller 520 may be the memory controller 300 illustrated in FIG. 1.

According to an exemplary embodiment, the memory controller 520, whichmay control the operations of the semiconductor memory device 100, maybe implemented as a part of the host 510 or as a separate chip.

FIG. 12 is a block diagram of a computer system 600 including thesemiconductor memory device 100 of FIG. 1 according to an exemplaryembodiment of the present inventive concept. The computer system 600 maybe implemented as an image processing device like a digital camera, acellular phone equipped with a digital camera, or a smart phone equippedwith a digital camera.

The computer system 600 includes a host 610, the semiconductor memorydevice 100 and a memory controller 620 controlling the data processingoperations, such as a write operation or a read operation, of thesemiconductor memory device 100. The computer system 600 furtherincludes an image sensor 630 and a display 640

The image sensor 630 included in the computer system 600 convertsoptical images into digital signals and outputs the digital signals tothe host 610 or the memory controller 620. The digital signals may becontrolled by the host 610 to be displayed through the display 640 orstored in the semiconductor memory device 100 through the memorycontroller 620.

Data stored in the semiconductor memory device 100 may be displayedthrough the display 640 according to the control of the host 610 or thememory controller 620. The memory controller 620, which may control theoperations of the semiconductor memory device 100, may be implemented asa part of the host 610 or as a separate chip.

FIG. 13 is a block diagram of a computer system 700 including thesemiconductor memory device 100 of FIG. 1 according to an exemplaryembodiment of the present inventive concept. The computer system 700includes the semiconductor memory device 100 and a host 710 controllingthe operations of the semiconductor memory device 100.

The computer system 700 also includes a system memory 720, a memoryinterface 730, an error correction code (ECC) block 740, and a hostinterface 750.

The system memory 720 may be used an operation memory of the host 710.The system memory 720 may be implemented by a non-volatile memory likeread-only memory (ROM) or a volatile memory like static random accessmemory (SRAM).

The host 710 connected with the computer system 700 may perform datacommunication with the semiconductor memory device 100 through thememory interface 730 and the host interface 750.

The ECC block 740 is controlled by the host 710 to detect an error bitincluded in data output from the semiconductor memory device 100 throughthe memory interface 730, correct the error bit, and transmit theerror-corrected data to the host through the host interface 750. Thehost 710 may control data communication among the memory interface 730,the ECC block 740, the host interface 750, and the system memory 720through a bus 770. The computer system 700 may be implemented as a flashmemory drive, a USB memory drive, an IC-USB memory drive, or a memorystick.

FIG. 14 is a block diagram of a computer system 800 including thesemiconductor memory device 100 of FIG. 1 according to an exemplaryembodiment of the present inventive concept. The computer system 800 maybe implemented as a host computer 810 and a memory card or a smart card.The computer system 800 includes the host computer 810 and the memorycard 830.

The host computer 810 includes a host 840 and a host interface 820. Thememory card 830 includes the semiconductor memory device 100, a memorycontroller 850, and a card interface 860. The memory controller 850 maycontrol data exchange between the semiconductor memory device 100 andthe card interface 860. The memory controller 850 may be the memorycontroller 300 illustrated in FIG. 1.

According to an exemplary embodiment, the card interface 860 may be asecure digital (SD) card interface or a multi-media card (MMC)interface, but the present inventive concept is not limited to thecurrent embodiments.

When the memory card 830 is installed into the host computer 810, thecard interface 860 may interface the host 840 and the memory controller850 for data exchange according to a protocol of the host 840. The cardinterface 860 may support a universal serial bus (USB) protocol and aninterchip (IC)-USB protocol. Here, the card interface 860 may indicate ahardware supporting a protocol used by the host computer 810, a softwareinstalled in the hardware, or a signal transmission mode.

When the computer system 800 is connected with the host interface 820 ofthe host computer 810 such as a PC, a tablet PC, a digital camera, adigital audio player, a cellular phone, a console video game hardware,or a digital set-top box, the host interface 820 may perform datacommunication with the semiconductor memory device 100 through the cardinterface 860 and the memory controller 850 according to the control ofthe host 840.

FIG. 15 is a block diagram of a computer system 900 including thesemiconductor memory device 100 of FIG. 1 according to an exemplaryembodiment of the present inventive concept. The computer system 900includes the semiconductor memory device 100, a memory controller 150, aprocessor 920 a first interface 930 and a second interface 940 which areconnected to a data bus 910.

According to an exemplary embodiment, the computer system 900 mayinclude a portable device such as a mobile phone, MP3 (MPECG AudioLayer-3) player, or MP4 (MPECG Audio Layer-4) player, a personal digitalassistant (PDA), or a portable media player (PMP).

According to an exemplary embodiment, the computer system 900 mayinclude a data processing system such as a personal computer (PC), anotebook-sized personal computer or a laptop computer.

According to an exemplary embodiment, the computer system 900 mayinclude a memory card such as a secure digital (SD) card or a multimediacard (MMC)

According to an exemplary embodiment, the computer system 900 mayinclude a smart card or a solid state drive (SSD)

The semiconductor memory device 100, the memory controller 150 and theprocessor 920 may be implemented as one chip, for example, a system onchip (SoC) or as separate devices.

According to an exemplary embodiment, the processor 920 may process datainput through the first interface 930 and write the data in thesemiconductor memory device 100.

According to an exemplary embodiment, the processor 920 may read datafrom the semiconductor memory device 100 and output the data through thefirst interface 930. In this case, the first interface 930 may be aninput/output device.

The second interface 940 may be a wireless interface for wirelesscommunication.

According to an exemplary embodiment, the second interface 940 may beimplemented by software or firmware.

FIG. 16 is a block diagram of a data processing system 1000 includingthe semiconductor memory device 100 of FIG. 1 according to an exemplaryembodiment of the inventive concept. In FIG. 16, MOD(E/O) denotes anoptical modulator used as an E/O converter which converts electricalsignal to optical signal, and DEM(O/E) denotes an optical demodulatorused as an O/E converter which converts optical signal to electricalsignal. Referring to FIG. 16, the data processing system 1000 includes acentral processing unit (CPU) 1010, a plurality of data buses 1001-1,1001-2, and 1001-3, and a plurality of memory modules 1040.

Each of the memory modules 1040 may transmit and receive optical signalsthrough a plurality of couplers 1011-1, 1011-2, and 1011-3 respectivelyconnected to the data buses 1001-1 through 1001-3. According to anexemplary embodiment, each of the couplers 1011-1 through 1011-3 may beimplemented by an electrical coupler or an optical coupler.

The CPU 1010 includes a first optical transceiver 1016, which includesat least one optical modulator MOD(E/O) and at least one opticaldemodulator DEM(O/E), and a memory controller 1012. The opticaldemodulator DEM(O/E) is used as an O/E converter. The memory controller1012 is controlled by the CPU 1010 to control the operations, e.g., thetransmitting operation and the receiving operation, of the first opticaltransceiver 1016.

For instance, during a write operation, a first optical modulatorMOD(E/O) of the first optical transceiver 1016 generates a modulatedoptical signal ADD/CTRL from addresses and control signals and transmitsthe optical signal ADD/CTRL to the optical communication bus 1001-3 incompliance with the memory controller 1012.

After the first optical transceiver 1016 transmits the optical signalADD/CTRL to the optical communication bus 1001-3, a second opticalmodulator MOD(E/O) of the first optical transceiver 1016 generatesmodulated optical write data WDATA and transmits the optical write dataWDATA to the data bus 1001-2.

Each of the memory modules 1040 includes a second optical transceiver1030 and a plurality of memory devices 100. Each memory module 1040 maybe implemented by an optical dual in-line memory module (DIMM), anoptical fully buffered DIMM, an optical small outline dual in-linememory module (SO-DIMM), an optical registered DIMM (RDIMM), an opticalload reduced DIMM (LRDIMM), an optical unbuffered DIMM (UDIMM), anoptical micro DIMM, or an optical single in-line memory module (SIMM).

Referring to FIG. 16, an optical demodulator DEM(O/E) included in thesecond optical transceiver 1030 demodulates the optical write data WDATAreceived through the data bus 1001-2 and transmits a demodulatedelectrical signal to at least one of the memory devices 100.

Each memory module 1040 may also include an electrical buffer 1033 whichbuffers an electrical signal output from an optical demodulatorDEM(O/E). For instance, the electrical buffer 1033 may buffer ademodulated electrical signal and transmits the buffered electricalsignal to at least one of the memory devices 100.

During a read operation, an electrical signal output from the memorydevice 100 is modulated into optical read data RDATA by an opticalmodulator MOD(E/O) included in the second optical transceiver 1030. Theoptical read data RDATA is transmitted to a first optical demodulatorDEM(O/E) included in the CPU 1010 through the data bus 1001-1. The firstoptical demodulator DEM(O/E) demodulates the optical read data RDATA andtransmits a demodulated electrical signal to the memory controller 1012.

FIG. 17 shows a multi-chip package 1100 including the semiconductormemory device 100 illustrated in FIG. 1. Referring to FIGS. 1 and 17,the multi-chip package 1100 may include a plurality of semiconductordevices, i.e., first through third chips 1130, 1140, and 1150 which aresequentially stacked on a package substrate 1110. Each of thesemiconductor devices 1130 through 1150 may include the semiconductormemory device 100. A memory controller (not shown) for controlling theoperations of the semiconductor devices 1130 through 1150 may beincluded within at least one of the semiconductor devices 1130 through1150 or may be implemented on the package substrate 1110. Athrough-silicon via (TSV) (not shown), a bonding wire (not shown), abump (not shown), or a solder ball 1120 may be used to electricallyconnect the semiconductor devices 1130 through 1150 with one other. Thememory controller (not shown) may be the memory controller 300illustrated in FIG. 1.

For example, the first semiconductor device 1130 may be a logic dieincluding an input/output interface and a memory controller and thesecond and third semiconductor devices 1140 and 1150 may be a die, onwhich a plurality of memory devices are stacked, and may include amemory cell array. At this time, a memory device of the secondsemiconductor device 1140 and a memory device of the third semiconductordevice 1150 may be the same or different types of memory.

Alternatively, each of the first through third semiconductor devices1130 through 1150 may include a memory controller. At this time, thememory controller may be on the same die as a memory cell array or maybe on a different die than the memory cell array.

As another alternative, the first semiconductor device 1130 may includean optical interface. A memory controller may be positioned in the firstor second semiconductor device 1130 or 1140 and a memory device may bepositioned in the second or third semiconductor device 1140 or 1150. Thememory device may be connected with the memory controller through a TSV.

The multi-chip package 1100 may be implemented using hybrid memory cube(HMC) in which a memory controller and a memory cell array die arestacked. When the HMC is used, the performance of memory devicesincreases due to the increase of bandwidth and the area of the memorydevices is minimized. As a result, power consumption and manufacturingcost can be reduced.

FIG. 18 is a three-dimensional conceptual diagram of an example 1100′ ofthe multi-chip package 1100 illustrated in FIG. 17. Referring to FIGS.1, 17 and 18, the multi-chip package 1100′ includes a plurality of thedies 1130 through 1150 connected with one another through TSVs 1160 in astack structure. Each of the dies 1130 through 1150 may include aplurality of circuit blocks (not shown) and a periphery circuit torealize the functions of the semiconductor memory device 100. The dies1130 through 1150 may be referred to as a cell array. The plurality ofcircuit blocks may be implemented by memory blocks.

The TSVs 1160 may be formed of a conductive material including a metalsuch as copper (Cu). The TSVs 1160 are arranged at the center of asilicon substrate. The silicon substrate surrounds the TSVs 1160. Aninsulating region (not shown) may be disposed between the TSVs 1160 andthe silicon substrate.

The present general inventive concept can also be embodied ascomputer-readable codes on a computer-readable medium. Thecomputer-readable recording medium is any data storage device that canstore data as a program which can be thereafter read by a computersystem. Examples of the computer-readable recording medium includeread-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetictapes, floppy disks, and optical data storage devices.

The computer-readable recording medium can also be distributed overnetwork coupled computer systems so that the computer-readable code isstored and executed in a distributed fashion. Also, functional programs,codes, and code segments to accomplish the present general inventiveconcept can be easily construed by programmers.

As described above, according to an exemplary embodiment of theinventive concept, a refresh operation is performed in a semiconductormemory device without receiving an external refresh command from amemory controller. In addition, a row decoder that performs activationof a word line in response to an activation command is separated from arow decoder that performs a refresh operation and the refresh operationis performed in the background in the semiconductor memory device 100,so that the operation speed of the semiconductor memory device 100 isincreased.

While the present inventive concept has been shown and described withreference to exemplary embodiments thereof, it will be apparent to thoseof ordinary skill in the art that various changes in form and detail maybe made therein without departing from the spirit and scope of theinventive concept as defined by the following claims.

1. A method of operating a semiconductor memory device comprising:receiving a bank address for a first bank including a first word line, asecond word line and a third word line; receiving a first row address toactivate the first word line for a read operation or a write operation;generating a second row address to refresh a plurality of memory cellsassociated with the second word line, wherein the semiconductor memorydevice generates the second row address.
 2. The method of claim 1,further comprising: if the first bank is not activated during a refreshwindow, generating a per-bank self-refresh signal.
 3. The method ofclaim 1, further comprising: activating the first word line using thefirst row address; and refreshing the plurality of memory cellsassociated with the second word line using the second row address. 4.The method of claim 3, wherein the activating and the refreshing areperformed at substantially the same time.
 5. The method of claim 3,further comprising: generating a refresh clock signal of which period isa refresh time interval, decreasing a counter value upon elapse of eachperiod of the refresh clock signal; and increasing the counter value inresponse to completion of the refreshing.
 6. (canceled)
 7. The method ofclaim 5, further comprising: generating a per-bank self-refresh signalassociated with the first bank if the counter value reaches apredetermined minimum value during a refresh window; performing theper-bank self-refresh signal on the first bank.
 8. The method of claim5, further comprising: generating a maximum refresh signal if thecounter value reaches a predetermined maximum value during a refreshwindow, wherein the generating of the second row address is prohibitedin response to the maximum refresh signal. 9.-10. (canceled)
 11. Themethod of claim 3, further comprising: decoding the second row address;generating a refresh done signal if the refreshing of the plurality ofmemory cells is completed. 12.-13. (canceled)
 14. The method of claim 7,further comprising: outputting an error signal to a memory controller ifa second activation command is issued to the bank during the performingof the per-bank self-refresh signal on the bank; performing the secondactive command after completion of the performing the per-bankself-refresh signal.
 15. A semiconductor memory device comprising: acommand decoder generating an activation command; a bank activationlogic receiving a bank address and the activation command and generatinga bank activation signal; a plurality of memory bank units including afirst bank unit, wherein if the bank address indicates to the first bankunit, the first bank unit performs the activation command and an activerefresh operation and generates a first refresh done signal, and if thebank address does not indicate to the first bank unit for apredetermined time, the first bank unit performs a per-bank self-refreshoperation, and wherein the performing of the activation command and theperforming of the active refresh operation are initiated by the bankactivation signal.
 16. The semiconductor memory device of claim 15,wherein the performing of the activation command and the performing ofthe active refresh operation start at substantially the same, andwherein after the performing of the active refresh operation iscompleted, the first refresh done signal is generated. 17.-19.(canceled)
 20. The semiconductor memory device of claim 15, wherein ifthe bank activation logic detects an activation conflict from the firstbank unit, the bank activation logic further generates an activationimpossibility signal and the generating of the bank activation signalfor the first bank unit is performed after completion of a firstper-bank self-refresh operation which is being performed on the firstbank unit, wherein the activation conflict occurs if the activationcommand is issued to the first bank unit which is performing the firstper-bank self-refresh operation.
 21. The semiconductor memory device ofclaim 20, further comprising: an error information generator receivingthe activation impossibility signal and providing error information to amemory controller.
 22. (canceled)
 23. The semiconductor memory device ofclaim 15, wherein the first bank unit comprises: a plurality of memoryblocks, wherein the memory blocks are arranged in an open bitlinearchitecture having a bitline sense amplifier shared by two adjacentblocks; a refresh row address generator generating a refresh activationaddress; a row decoder receiving a normal activation address and therefresh activation address; and wherein if the row decoder decodes therefresh activation address, the row decoder generates the first refreshdone signal, and wherein if the normal activation address is associatedwith a first word line within a first block and if the refreshactivation address is associated with a second word line within a secondblock which is spaced apart at least one block from the first block, therow decoder decodes the refresh activation address.
 24. Thesemiconductor memory device of claim 23, wherein if the second block isadjacent to the first block, the row decoder does not decode the refreshactivation address.
 25. The semiconductor memory device of claim 23,wherein the first bank unit further comprises: a first address driverreceiving a row address and providing the normal activation address tothe row decoder; a bank control logic receiving the per-bankself-refresh signal and the bank activation signal and generating a bankcontrol signal; and an activation controller receiving the bank controlsignal and generating a first activation signal and a second activationsignal, wherein the first activation signal is provided to the firstaddress driver, wherein the second activation signal is provided to therefresh row address generator, and wherein a logic level of the firstactivation signal and a logic level of the second activation signal aredetermined according to the bank control signal. 26.-31. (canceled) 32.A semiconductor memory system comprising: a memory controller issuing afirst activation command and a first row address; a semiconductor memoryreceiving the first activation command and the first row address,generating a second row address, and activating a first word lineselected by the first row address and refreshing a plurality of memorycells associated with the second row address, wherein the refreshing andthe activating are initiated by the first activation command.
 33. Thesemiconductor memory system of claim 32, wherein the activating and therefreshing start at substantially the same time.
 34. The semiconductormemory system of claim 32, wherein the semiconductor memory includes aplurality of bank units, wherein if a bank unit is not refreshed for arefresh window, the bank unit performs a per-bank self-refresh operationin response to a per-bank self-refresh signal generated from the bankunit, wherein if the first active command is issued to the bank unitwhich is performing the per-bank self-refresh operation, thesemiconductor memory sends error information to the memory controller,without performing the first active command.
 35. (canceled)
 36. Thesemiconductor memory system of claim 34, wherein the per-bankself-refresh operation is performed on remaining row addresses of thebank unit other than the second row address.